Green silicon carbide (SiC) is widely used in wafer polishing due to its unique properties, which offer several advantages over other abrasive materials like aluminum oxide or diamond. Here are the key benefits of using green silicon carbide for wafer polishing:
1. High Hardness (Mohs ~9.3)
Green SiC is harder than aluminum oxide (Mohs ~9) and nearly as hard as boron carbide (Mohs ~9.5), making it highly effective for polishing hard materials like silicon wafers, sapphire, and ceramics.
While not as hard as diamond (Mohs 10), it provides a cost-effective alternative for many applications.
2. Sharp and Angular Abrasive Particles
The grains fracture easily during polishing, creating fresh cutting edges that maintain consistent material removal rates.
This self-sharpening property ensures prolonged abrasive efficiency.
3. Chemical Stability & Purity
Green SiC is synthesized with high purity (≥99%), minimizing contamination risks in semiconductor wafer processing.
It is chemically inert in many polishing environments, reducing unwanted reactions with the wafer surface.
4. Controlled Surface Finishing
Provides a balance between material removal rate and surface smoothness, making it suitable for both rough and fine polishing stages.
Produces less sub-surface damage compared to coarser abrasives like black SiC.
5. Thermal Conductivity & Heat Resistance
High thermal conductivity helps dissipate heat during polishing, reducing thermal stress on wafers.
Stable at high temperatures, preventing degradation during high-speed polishing.
6. Cost-Effectiveness
More affordable than diamond abrasives while still delivering high performance for many wafer types (e.g., silicon, quartz, and glass).
7. Versatility in Applications
Used for polishing monocrystalline and polycrystalline silicon wafers, as well as non-semiconductor materials like optical glass and ceramics.
Compatible with both free abrasive slurries and fixed abrasive pads.
Comparison with Other Abrasives
| Property | Green SiC | Black SiC | Alumina (Al₂O₃) | Diamond |
|---|---|---|---|---|
| Hardness (Mohs) | 9.3 | 9.2 | 9.0 | 10 |
| Purity | Very High | Moderate | High | Highest |
| Cost | Moderate | Low | Low | Very High |
| Best Use Case | Fine polishing | Rough grinding | General polishing | Ultra-precision |
Conclusion
Green silicon carbide is ideal for wafer polishing where a combination of hardness, purity, and controlled material removal is required. It bridges the gap between cost-effective alumina and ultra-expensive diamond abrasives, making it a preferred choice for semiconductor and optical industries.